基于TrueTime的非线性网络控制系统

针对非线性系统往往具有不确定性、结构复杂、建模困难、难于在网络条件下进行仿真研究的问题,建立了一个基于TrueTime的非线性网络控制系统.在对弹簧连接的双倒立摆耦合非线性系统模型进行Matlab/Simulink模块化建模的基础上,结合TrueTime的网络通信模块,利用设计的鲁棒控制器将对象模型的不确定性和网络时延的不确定性进行了综合处理.仿真结果表明,该系统不仅降低了非线性系统建模的复杂性,而且为研究网络控制系统结构下非线性系统的动态特性提供了条件.     

基于数据的多模型分数阶PID控制方法

针对复杂非线性系统,将多模型建模与分数阶PID控制相结合,设计了一种完全基于输入-输出数据的多模型在线建模控制方法.首先,利用输入-输出数据对非线性系统进行在线多模型建模;然后,针对所建立的多个局部模型,基于加权控制方式设计分数阶PID控制器.该方法将对系统的建模与控制器的设计包含在一个控制系统设计框架以内,对系统模型的不确定性具有更好的鲁棒性,仿真实验的结果表明了该方法的有效性.     

基于模糊RBF神经网络整定的航空发动机多变量解耦控制

为解决航空发动机控制变量之间的强耦合性,构造了基于模糊RBF神经网络整定的航空发动机多变量解耦控制系统.设计了基于模糊RBF神经网络的多变量解耦控制器,在线调整PID控制器的参数并根据Delta学习规则对网络权值进行修正以达到最佳控制;针对某型航空发动机含未建模动态和噪声等随机干扰的非线性模型进行了多变量解耦控制系统仿真.结果表明:系统具有满意的动态性能和解耦特性,该方法不需要知道发动机的精确数学模型,对航空发动机的非线性和不确定性具有较强的自适应能力.     

参数不确定网络拥塞系统的保性能控制

针对网络控制系统在建模过程中普遍存在的参数不确定性问题,在现有的网络拥塞控制模型基础上,考虑了系统具有时变参数不确定性的情况.通过对已有非线性动态TCP模型进行线性化,得到一个带有参数不确定性的线性时变系统,并且,该线性系统模型能够更精确描述原来非线性系统.对于已得到的线性系统,利用Lyapunov稳定性理论,以及结合...     

一种改进的线性网络控制系统的鲁棒稳定性分析

考虑在网络传输延迟和数据丢包二者共同影响下的具有时变结构不确定性的线性网络控制系统的稳定性问题.首先采用模型变化方法,将网络控制系统模型转换为时滞系统模型;然后,通过引入一种新的考虑网络传输延迟下界的Lyapunov泛函,对具有结构不确定性的时变时滞系统的稳定性进行分析,给出了时滞相关的系统镇定的线性矩阵不等式条件.最后通过数值实例证明本文方法与现有方法相比具有更小的保守性.     

一种改进的线性网络控制系统的鲁棒稳定性分析

考虑在网络传输延迟和数据丢包二者共同影响下的具有时变结构不确定性的线性网络控制系统的稳定性问题.首先采用模型变化方法,将网络控制系统模型转换为时滞系统模型;然后,通过引入一种新的考虑网络传输延迟下界的Lyapunov泛函,对具有结构不确定性的时变时滞系统的稳定性进行分析,给出了时滞相关的系统镇定的线性矩阵不等式条件.最后通过数值实例证明本文方法与现有方法相比具有更小的保守性.     

网络化时延补偿策略及其在三容系统中的应用

网络诱导时延在网络控制系统中是不可避免的,并且对控制系统性能有非常重要的影响.为了解决网络化控制系统的时延问题,研究了具有时变传输时延的网络化控制系统的稳定性问题.时变的时延可以看作是平均时延和不确定时延之和.具有长时延的网络控制系统可以建模为具有结构不确定性的离散时间模型.基于这个模型,通过求解一个迭代linear matrix inequality,给出了使闭环系统稳定的控制器.通过对三容系统的仿真研究,证实了所提方案的有效性.     

基于广义系统的网络控制系统的分析与建模

对具有分布时延、动态输出反馈控制器且被控对象为广义系统的多输入多输出网络控制系统,在传感器和控制器时钟驱动、异步采样,执行器事件驱动情况下的运行特性进行了分析·在分析的基础上建立了正则、无脉冲广义系统对象的多输入多输出网络控制系统数学模型·通过电力系统中一个呈现广义系统模型的控制实例,说明了建模方法的有效性·为被控对象呈现广义系统模型的网络控制系统的性能分析和设计给出了有益的尝试·     

基于多模型在线辨识的滑模变结构控制

为了改善复杂非线性系统中传统滑模变结构控制系统的控制效果,提出了一种将多模型在线建模与滑模变结构控制结合的方案.首先,根据输入输出数据利用在线数据聚类的方法建立多个局部模型,实时对局部模型进行更新,并通过加权综合获得非线性系统的在线辨识模型;然后,针对系统的辨识模型设计基于趋近律的滑模变结构控制器.仿真结果表明,控制方案对系统模型的不确定性具有良好的鲁棒性.     

不确定网络控制系统的死区调度与控制协同设计方法

针对具有不确定性的多输入多输出(MIMO)网络控制系统,提出了1种调度与控制协同设计方法。为改善网络服务质量(Qo S),将死区调度策略应用于MIMO网络控制系统,并将该系统建模为一类具有不确定性和时延的离散线性系统。为补偿网络诱导时延的影响,构造了1种状态观测器和反馈控制器。基于Lyapunov函数法和锥补线性化方法,给出了系统渐近稳定的充分条件及控制器设计的迭代求解法。针对死区阈值的优化,提出了1种基于二分法的阈值优化迭代算法。仿真算例表明该文方法是有效的。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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